To locate and quantify local damage in a simply supported bridge, in this study, we derived a rotational-angle influence line equation of a simply supported beam model with local damage. Using the diagram multiplicati...To locate and quantify local damage in a simply supported bridge, in this study, we derived a rotational-angle influence line equation of a simply supported beam model with local damage. Using the diagram multiplication method, we introduce an analytical formula for a novel damage-identification indicator, namely the diff erence of rotational-angle influence linescurvature(DRAIL-C). If the initial stiff ness of the simply supported beam is known, the analytical formula can be effectively used to determine the extent of damage under certain circumstances. We determined the effectiveness and anti-noise performance of this new damage-identification method using numerical examples of a simply supported beam, a simply supported hollow-slab bridge, and a simply supported truss bridge. The results show that the DRAIL-C is directly proportional to the moving concentrated load and inversely proportional to the distance between the bridge support and the concentrated load and the distance between the damaged truss girder and the angle measuring points. The DRAIL-C indicator is more sensitive to the damage in a steel-truss-bridge bottom chord than it is to the other elements.展开更多
针对基于时频分析的瞬时转频估计问题及现有方法在抗噪性和估计精度方面的不足,引入一种新兴的强抗噪性的时频分析方法——时频聚集(Concentration of Frequency and Time,ConceFT),提出ConceFT联合峰值搜索的瞬时转频估计方法。仿真试...针对基于时频分析的瞬时转频估计问题及现有方法在抗噪性和估计精度方面的不足,引入一种新兴的强抗噪性的时频分析方法——时频聚集(Concentration of Frequency and Time,ConceFT),提出ConceFT联合峰值搜索的瞬时转频估计方法。仿真试验中,测试了不同信噪比下的线调频信号和正弦调频信号的瞬时转频估计,结果表明该方法能够有效抑制强噪声干扰,准确估计瞬时转频,在信噪比大于-20 dB时能保证估计误差在3%以内;该方法分别用于转速上升和转速复杂波动的滚动轴承振动信号分析,均能以高精度提取出瞬时转频曲线。与经典的短时傅里叶联合峰值搜索方法对比,在抗噪性及估计精度上均有显著提高。展开更多
基金supported by the National Natural Science Foundation of China(Nos.51608245 and 51568041)Natural Science Foundation of Gansu Province(Nos.148RJZA026 and 2014GS02269)
文摘To locate and quantify local damage in a simply supported bridge, in this study, we derived a rotational-angle influence line equation of a simply supported beam model with local damage. Using the diagram multiplication method, we introduce an analytical formula for a novel damage-identification indicator, namely the diff erence of rotational-angle influence linescurvature(DRAIL-C). If the initial stiff ness of the simply supported beam is known, the analytical formula can be effectively used to determine the extent of damage under certain circumstances. We determined the effectiveness and anti-noise performance of this new damage-identification method using numerical examples of a simply supported beam, a simply supported hollow-slab bridge, and a simply supported truss bridge. The results show that the DRAIL-C is directly proportional to the moving concentrated load and inversely proportional to the distance between the bridge support and the concentrated load and the distance between the damaged truss girder and the angle measuring points. The DRAIL-C indicator is more sensitive to the damage in a steel-truss-bridge bottom chord than it is to the other elements.
文摘针对基于时频分析的瞬时转频估计问题及现有方法在抗噪性和估计精度方面的不足,引入一种新兴的强抗噪性的时频分析方法——时频聚集(Concentration of Frequency and Time,ConceFT),提出ConceFT联合峰值搜索的瞬时转频估计方法。仿真试验中,测试了不同信噪比下的线调频信号和正弦调频信号的瞬时转频估计,结果表明该方法能够有效抑制强噪声干扰,准确估计瞬时转频,在信噪比大于-20 dB时能保证估计误差在3%以内;该方法分别用于转速上升和转速复杂波动的滚动轴承振动信号分析,均能以高精度提取出瞬时转频曲线。与经典的短时傅里叶联合峰值搜索方法对比,在抗噪性及估计精度上均有显著提高。
